Project 1 will investigate means of improving the survival of patients with myeloid malignancies by reducing transplant-related mortality and relapse. In Project A, a regimen of cyclophosphamide (CY), total body irradiation (TBI) (15.75 Gy) and pentoxifylline (PTX) will be evaluated in patients with acute myeloid leukemia in first or second remission or untreated first relapse. Effects on relapse and transplant-related mortality will be determined. In Project B, attempts will be made to improve the survival of patients with chronic myeloid leukemia by comparing a regimen of busulfan (BU)/CY with CY/TBI. Attempts will be made to evaluate the significance of posttransplant relapse as defined by clinical, cytogenetic and PCR analyses. An attempt will be made to evaluate the practicality and benefits of interferon treatment prior to hematologic relapse. We will also carry out transplant studies in older patients (under age 66). In Project C, BU pharmacokinetics will be evaluated in patients receiving BU/CY/TBI. BU does will be specifically adjusted on the basis of predicted plasma levels for individual patients. If toxicity is diminished a dose escalation study based on targeted plasma levels will be carried out. If the dose escalation study is successful phase II and III studies will be carried out at the MTD based on targeted blood levels. Growth factors and pentoxifylline will be evaluated following completion of these studies.